Fiber fractionating apparatus and process



Oct. 10,1967 J. J. A FRANCA; JR.. ETAL 3,346,110 FIBER FRACTIONATING APPARATUS AND l ROCESS 4 Filed Oct. 22, 1965 3 Sheets-Sheet 1 m m m JOSEPH J. LAFRANCA,JR. MAYER MAYER, JR.

SUCTION MEANS HEBER W.WELLER,JR.

FIG I ATTORNEY Oct. 10, 1967 J. J. LA FRA'NCA, JR.. EATAL 10 FIBER FRACTIONATING APPARATUS AND PROCESS Filed Oct. 22, 1965 INVENTORS JOSEPH -J. LAFRANCA, JR. MAYER MAYER,JR. HERBER w. WELLER,JR.

BY A I,

' ATTORNEY 3 Sheets-Sheei 2 Oct. 10, 1967 J. J. LA FRANCA, JR., ETAL 3,346,110

FIBER FRACTIONATING APPARATUS AND PROCESS 3 Sheets-Sheet 2" Filed Oct. 22, 1965 INVENTORS JOSEPH J. LAFRANCA,JR. MAYER MAYER, JR.

HEBER w. WELLER, JR. 1

ATTORNEY United States Patent 3,346,110 FIBER FRACTIONATING APPARATUS AND PROCESS Joseph J. Lafranca, Jr., Metairie, Mayer Mayer, Jr., New

Orleans, and Heber W. Weller, Jr., Metairie, La., assignors to the United States of America as represented by the Secretary of Agriculture Filed Oct. 22, 1965, Ser. No. 502,747 5 Claims. (Cl. 2092) A non-exclusive, irrevocable, royalty-free license in the invention herein described, for all governmental purposes, throughout the world, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to an apparatus for :fractionating fibers into length-groups.

The present application is a continuation-in-part of the copending application of Joseph J. Lafranca, Jr., Mayer Mayer, Jr., and Heber W. Weller, Jr., Serial No. 374,863, filed June 12, 1964. In this copending application, an embodiment of the fiber fractionating apparatus was disclosed, but not claimed. The instant application relates to that embodiment.

More specifically, it relates to an apparatus for electrostatically aligning fibers and separating the aligned fibers into fractions having specific lengths.

Still more specifically, it relates to an apparatus for removing short fibers from cotton lint. Another object of our invention is to provide a novel process for determining fiber-length distribution.

As used herein, the term fibers relates to the individual components of cellulosic or noncellulosic staple textile materials such as cotton, regenerated cellulose, polyester, polyamide, polyvinyl, the natural nitrogen-containing fibers, and the like. Because of its wide use, cotton will frequently be referred to below as the fiber, but it is to be understood that this usage is illustrative only. a

The term lint as used herein, relates to a collection of fibers of various lengths. The term short fibers relates to the shorter portionsof the lint, usually portions of fibers not longer than about three-eighths inch.

The presence of these short fibers has several disadvantages in the processing of lint cotton into yarn and/ or fabric. In the first place, short fibers reduce the strength of the yarn. This results in a greater number of ends down or breakages during the spinning process thereby decreasing the efiiciency of the process and increasing the cost. In the second place, these shorter fibers increase the total number of ends per unit length of the resulting yarn. These ends tend to protrude and impart a fuzzy character detrimental to the quality of the yarn. In the third place, when these fuzzy yarns are died, the fiber ends do not take'the same color but reflect light'Consequently, the fabric or yarn does not acquire as strong a shade as the amount of dye used should produce. In the fourth place, yarns produced without these shorter fibers are characterized by their increased strength, their evenness, their smoothness, their uniformity, and their commercial desirability. V

In the past, these short fibers have been removed only by a low-capacity, costly, combing process. Because of the great expense involved, generally only lint or fibers having a classers staple length of at least about 1% inches, the more expensive of the cotton fibers, have been subjected to the combing operation. Therefore, it will be seen that prior to this invention there still remained a need for a practical means of eliminating the shorter fibers from lint. Such a means should be economically adaptable to the removal from lint of short fibers having a length of not more than inch. Lastly, but not least important, the means should not break or otherwise physically damage the fibers.

In the copending application cited above, the apparatus for fractionating loose masses of relatively disoriented fibers into different length groups comprises electrode members angularly positioned with means for transporting the fibers interposed between the two electrodes. One of the electrodes is curved and the other is essentially flat. It is characteristic of the two electrodes that the edges of the electrodes having the maximum potential gradient between them are parallel and the two edges having the minimum potential gradient between them are also parallel, the edges being parallel to the direction of travel of the transporting means. However, the distance between the edges having the minimum and maximum potential gradients between them is different. If planes are constructed across the region between the two electrodes, said planes being perpendicular to the edges having maximum or minimum potential gradient between them, the areas of these cross-sections are constant. In other Words, the curved electrode is curved only in two directions.

In the instant invention, as will be apparent from the detailed description of the drawings below, the apparatus also comprises two elongated, opposed electrodes, one multicurved or shaped like a bow with recurvate ends and the other substantially flat with means for transporting the fibers interposed between the two electrodes. In the instant invention, the edges of the two electrodes parallel to the direction of travel of the transporting means, i.e., in the longitudinal direction of. the electrodes, also are parallel. Further, the distance between the edges of the arcuate and the preferably fiat electrodes on each edge of the transportation means is equal, and is the minimum distance between the two electrodes. This establishes at least two regions of maximum field intensity. Further, when planes .are constructed across the region between the two electrodes, said planes being perpendicular to the edges having maximum potential, the crosssectional area of each plane varies from the area of the next adjacent plane. In other words, the arcuate elec trode is curved in three directions. In the accompanying drawings, the spatial directions are designated by the letters x, y and z, where z is the direction from input to output of the fibers, i.e., the direction of the longitudinal axes of the electrodes; y is the direction between the two edges of the transporting means, i.e., transverse to the latter and also to the electrodes; and x is the direction perpendicular to the preferably fiat electrode.

The apparatus which is the subject of our invention comprises any suitable means for introducing loose masses of relatively untangled, individualized fibers into an electrostatic field having a nonuniform potential gradient producedby the specially shaped and positioned electrodes.

As noted above, the surfaces of one, or both, of said electrodes are multicurved to form both concave and convex portions. The concave portion, as viewed from the opposing electrode, forms the low-potential gradient region of the field while the convex portions, as viewed from the opposing electrode, form the high-potential gradient regions of the field.

In the process of our invention, loose masess of relatively untangled, individualized fibers are introduced into the region of lowest potential gradient between the electrodes. Upon entering the electrostatic field, these individualized fibers align themselves parallel to the lines of force between the electrodes and are in general perpendicular to the electrodes and move in the direction of increasing field gradient, the longer fibers moving. more rapidly. The short fibers are relatively unalfected and re main in the region of lowest field intensity which, in the apparatus of our invention is at, or near, the bottom of the concave portion as viewed from the opposing electrode.

The individually aligned and erect fibers are then withdrawn from the output-end of the electrostatic field by any suitable means. We prefer to use suction air. The fractionated fibers are then collected on any suitable means, such as wire screens or perforated plates in a receptacle (or chamber), and recovered.

One but not necessarily the only embodiment of an apparatus suitable for the practice of our invention is shown in the accompanying drawings in which:

FIGURE 1 is a three-dimensional view showing the essential features of the invention.

FIGURE 2 is a plan (xy) view showing transverse arrangement of electrodes.

FIGURE 3 is a sectional (x-z) view showing longitudinal arrangement of electrodes.

FIGURE 4 shows a modification of the apparatus in which means for transporting fibers through the electrostatic field also serves as one of the electrodes, as described more fully below.

Referring to FIGURE 1, the loose masses of relatively untangled disoriented fibers 11 are fed from supply duct 12 into the region of maximum distance between multicurved electrode 13 and substantially fiat electrode 14. This is the (concave) low field gradient region. Electrodes 13 and 14 are energized through conductors 15 and 16 with a potential which may be either alternating or, preferably, direct. Either of these potentials may be supplied by any means (not shown) common to the art. Although not so limited, we prefer to have electrode 13 grounded through conductor 15. A continuously traveling endless belt 17 travels in the direction from fiber feed (input) to discharge (output) over rolls 18 and 19 which are rotatably mounted in conventional bearings 34, 36, 37, and a fourth bearing (not shown), and driven by any conventional means such as motor 20 through pulleys 21 and 22 by belt 23. The endless belt 17 may be of any suitable conductive or nonconductive material; however, we prefer to use a nonconductive webbing such as vinylcoated canvas fabric.

A modification of the above described apparatus is shown in FIGURE 4. In this modification, a flexible belt 40, such as rubber impregnated with a conductive metallic powder 41, is used. When such a belt is employed, only the side next to fibers 11 is impregnated with the metallic powder. The powder may be any commerciallyavailable corrosion-resistant material, aluminum powder causing excellent results to be obtained. Use of such a belt would eliminate the need for the substantially flat electrode 14 provided conductor 16 is in electrical contact with the conductive side of the belt, 40, as shown in FIGURE 4.

Fibers fed from duct 12 coming under the influence of the electrostatic field at the region of minimum field strength become individualized and oriented in a direction parallel to the lines of force of the field. As a result of the nonuniform transverse (y-direction) potential gradient, the longer fibers migrate rapidly toward the sides of the belt having the higher field strength, while the shorter fibers remain at or near the concave portion of the multicurved electrode. As noted above and described and claimed in copending application of Mayer Mayer, ]r., Heber W. Weller, Jr., and Joseph J. Lafranca, Jr., Ser. No. 374,863, filed June 12, 1964, under the influence of the electrostatic field the fibers tend to migrate and align themselves in an increasing order of fiber length in the direction of increasing field strength. Furthermore, as will be readily apparent to those skilled in the art from FIGURE 1, the distance between the concave portion of electrode 13 and the flat electrode 14 decreases in the direction from the input to the output end, resulting also in an increasing potential gradient in the direction of travel. As a result of this longitudinally in- 4 creasing potential gradient along the z-axis, fiber travel through the electrostatic field is effected more rapidly than by the travel of the endless belt alone.

The erect fibers which are thus aligned and segregated by length may be differentially removed or picked off in fractions in any suitable manner such as suction air either just before or immediately after leaving the electrostatic field, such means being known to those skilled in the art.

In FIGURE 1 we have shown one fiber removal arrangement which incorporates a vacuum chamber 24. Said chamber 24 is divided into subchambers 25, 26, and 27 by partitions 28 and 29 which are positioned so that the processed fibers can be diiferentially removed by length into two groups, those longer than, and those equal to and shorter than, some predetermined length. The longer fraction of fibers removed in subchambers 25 and 26 is conveyed by ducts 30 and 31 into a fiber retriever (not shown) while the shorter fraction removed in subchamber 27 is conveyed by duct 32 into another fiber retriever (also not shown). Chamber 24 may be subdivided into as many subchambers as desired and by providing each subchamber with an outlet duct and fiber retriever the fibers may be fractionated into as many length groups as desired. As mentioned above, the fractions may be removed by suction air induced by means known in the art. Such conventional means are shown schematically as boxes, bearing the legend Suction Means, connected to each of ducts 30, 31, and 32.

It is a critical feature of the apparatus of this invention that the proximity of the two electrodes in the high intensity region be spaced not less than the average length of the longer fibers.

It is an advantage of the apparatus of this invention that several concave and convex portions of the multicurved plate may be used by extending the width of the electrodes in the y direction. However, when this is done it is necessary that each concave portion be equipped with its own fiber input and output.

These and other advantages will be apparent to those skilled in the art.

We claim:

1. Apparatus for fractionating loose masses of disoriented textile fibers into different length groups comprising:

(a) an elongated, substantially flat first electrode and an elongated, multicurved, second electrode opposed to and substantially coextensive therewith, said electrodes together defining a fiber fractionating zone having an input end and an output end, the opposing longitudinal edges of said electrodes being parallel and equidistant from each other and spaced not less than the average length of the longest textile fibers to be fractionated, said second electrode having longitudinally extending convex surfaces near the edges and a longitudinally extending concave surface centrally positioned between said convex surfaces, the perpendicular distance between the centerline of said concave surface and the substantially fiat electrode surface decreasing in the direction from the input to the output end;

(b) means connected to the electrodes for energizing said electrodes to produce an electrostatic field of nonuniform potential gradient therebetween in the aforesaid fiber fractionating zone, said potential gradient being lowest between the central concave portion of the multicurved electrode and the flat electrode and increasing both nonuniformly outward toward the edges of said electrodes and uniformly in the direction from the input end to the output end of the fiber fractionating zone defined by said electrodes;

(c) endless, nonconducting transport means positioned between the electrodes within the fiber fractionating zone;

(d) means adjacent the input end of the fiber fractionating zone for continuously feeding a mass of disoriented fibers of nonuniform length onto said transport means;

(e) means connected to said transport means for continuously moving it in a longitudinal direction through the fiber fractionating zone;

(f) compartmented fiber receiving means adjacent the output end of the fractionating zone positioned in a lateral, contiguous relation to the transport means; and

(g) means for removing fractionated fibers of different lengths from said transport means and for depositing said fibers in said receiving means.

2. The apparatus of claim 1 wherein the nonconducting transport means comprises a vinyl coated fabric endless belt.

3. Apparatus for fractionating loose masses of disoriented textile fibers into different length groups comprising:

(a) a multicurved elongated first electrode having straight longitudinal edges lying in one plane, longitudinally extending convex surfaces adjacent each edge, and a central, longitudinally extending concave surface, the perpendicular distance from the center of the concave surface to the plane of the edges being greater at one end of said first electrode than at the other;

(b) endless transport means substantially coextensive with the first electrode forming a loop having a first run proximal to said first electrode and a second run distal to said first electrode, said endless transport means having an outer electrically conductive surface constituting a second electrode and an inner electrically conductive surface constituting a second electrode and an inner electrically nonoonducting surface, said endless transport means being so disposed that at least said first run extends longitudinally with respect to said first electrode and lies in a plane parallel to the longitudinal edges of said first electrode, said endless transport means being also so disposed that the outer electrically conductive surface of said first run together with said first electrode defines a fiber fractionating zone having an input end and an output end, the end having the greater perpendicular distance between the center of the concave surface and the plane of the edges of the first electrode constituting the input end of said zone, the distance between the outer surface of said first run and the plane of the edges of the first electrode being not less than the average length of the longest textile fibers to be fractionated;

(c) separate means connected to said first and second electrodes for energizing said electrodes to produce an electrostatic field of nonuniform potential gradient therebetween in the aforesaid fiber fractionating zone, said potential gradient being lowest between the central concave portion of the first electrode and the transport means and increasing both nonuniformly outward toward the edges and uniformly in the direction from the input end to the output end of the fiber fractionating zone;

(d) means adjacent the input end of the fiber fraction ating zone for continuously feeding a mass of disoriented fibers of nonuniform length onto said transport means;

(e) means connected to said transport means for continuously moving it in a longitudinal direction through the fiber fractionating zone;

(f) compartmented fiber receiving means adjacent the output end of the fractionating zone positioned in a lateral, contiguous relation to the transport means; and

(g) means for removing fractionated fibers of different lengths from said transport means and for depositing said fibers in said receiving means.

4. The apparatus of claim 3 wherein the transport means comprises an endless, electrically nonconductive belt the outer surface of which is impregnated with a conductive metal powder.

5. A process for fractionating loose masses of disoriented textile fibers into individualized oriented length groups comprising:

(a) producing an elongated electrostatic field in which the field intensity and potential gradient in a plane transverse to the length of the field is lowest at the center and the potential gradient increases nonuniformly outward toward the edges, in which the potential gradient is uniform and is a maximum along the longitudinal edges, and in which the potential gradient increases uniformly along the longitudinal axis of the field from a minimum at one end to a maximum at the other end;

(b) introducing a mass of disoriented fibers into the end having the lowest uniform and nonuniform potential gradients whereupon the disoriented fibers become individualized and oriented parallel to the lines of force of said field;

(c) moving said fibers through the electrostatic field in a longitudinal direction substantially parallel to the uniformly increasing field intensity whereupon the individualized and oriented fibers become aligned in orderly increasing length outwardly from the centerline of the field towards both edges thereof in the direction of the increasing nonuniform potential gradients;

(d) continuing the movement of the aligned end oriented fibers longitudinally through the field in the direction of uniformly increasing potential gradient until said fibers have traversed the length of the field;

(e) separately removing fibers of different lengths from the end of the electrostatic field.

References Cited UNITED STATES PATENTS FRANK W. LUTIER, Primary Examiner. 

1. APPARTUS FOR FRACTIONATING LOOSE MASSES OF DISORIENTED TEXTILE FIBERS INTO DIFFERENT LENGTH GROUPS COMPRISING: (A) AN ELONGATED, SUBSTANTIALLY FLAT FIRST ELECTRODE AND AN ELONGATED, MULTICURVED, SECOND ELECTRODE OPPOSED TO AND SUBSTANTIALLY COEXTENSIVE THEREWITH, SAID ELECTRODES TOGETHER DEFINING A FIBER FRACTIONATING ZONE HAVING AN INPUT END AND AN OUTPUT END, THE OPPOSING LONGITUDINAL EDGES OF SAID ELECTRODES BEING PARALLEL AND EQUIDISTANT FROM EACH OTHER AND SPACED NOT LESS THAN THE AVERAGE LENGTH OF THE LONGEST TEXTILE FIBERS TO BE FRACTIONATED, SAID SECOND ELECTRODE HAVING LONGITUDINALLY EXTENDING CONVEX SURFACES NEAR THE EDGES AND A LONGITUDINALLY EXTENDING CONCAVE SURFACE CENTRALLY POSITIONED BETWEEN SAID CONVEX SURFACES, THE PERPENDICULAR DISTANCE BETWEEN THE CENTERLINE OF SAID CONCAVE SURFACE AND THE SUBSTANTILLY FLAT ELECTRODE SURFACE DECREASING IN THE DIRECTION FROM THE INPUT TO THE OUTPUT END; (B) MEANS CONNECTED TO THE ELECTRODES FOR ENERGIZING SAID ELECTRODES TO PRODUCE AN ELECTROSTATIC FIELD OF NONUNIFORM POTENTIAL GRADIENT THEREBETWEEN IN THE AFORESAID FIBER FRACTIONATING ZONE, SAID POTENTIAL GRADIENT BEING LOWEST BETWEEN THE CENTRAL CONCAVE PORTION OF THE MULTICURVED ELECTRODE AND THE FLAT ELECTRODE AND INCREASING BOTH NONUNIFORMLY OUTWARD TOWARD THE EDGES OF SAID ELECTRODES AND UNIFORMLY IN THE DIRECTION FROM THE INPUT END TO THE OUTPUT END OF THE FIBER FRACTIONATING ZONE DEFINED BY SAID ELECTRODES; (C) ENDLESS, NONCINCUCTING TRANSPORT MEANS POSITIONED BETWEEN THE ELECTRODES WITHIN THE FIBER FRACTIONATING ZONE; (D) MEANS ADJACENT THE INPUT END OF THE FIBER FRACTIONATING ZONE FOR CONTINUOUSLY FEEDING A MASS OF DISORIENTED FIBERS OF NONUNIFORM LENGTH ONTO SAID TRANSPORT MEANS; (E) MEANS CONNECTED TO SAID TRANPORT MEANS FOR CONTINUOUSLY MOVING IT IN A LONGITUDINAL DIRECTION THROUGH THE FIBER FRACTIONATING ZONE; (F) COMPARTMENTED FIBER RECEIVING MEANS ADJACENT THE OUTPUT END OF THE FRACTIONATING ZONE POSITIONED IN A LATERAL, CONTIGUOUS RELATION TO THE TRANSPORT MEANS; AND (G) MEANS FOR REMOVING FRACTIONATED FIBERS OF DIFFERENT LENGTHS FROM SAID TRANSPORT MEANS AND FOR DEPOSITING SAID FIBERS IN SAID RECEIVING MEANS. 